is-animated is a simple library for detecting animated images, it supports not only GIFs, but also APNG and WebP images.
npm install is-animated
const fs = require('fs')
const isAnimated = require('is-animated')
const filename = process.argv[2]
fs.readFile(filename, (err, buffer) => {
const answer = isAnimated(buffer) ? 'Yes' : 'No'
console.log(`Is "${filename}" animated? ${answer}.`)
})